Known to the art are pillar measuring machines comprising a pair of lateral supporting structures, each constituted by a plurality of vertical pillars aligned with respect to one another and by a top horizontal fixed beam supported by the pillars. The fixed beams of the two supporting structures are parallel to one another and to a first co-ordinate axis of the machine. The machine moreover comprises a mobile beam, horizontal and transverse to the fixed beams, which is supported thereby and can slide in the direction of the first axis along guides made on the same fixed beams. The mobile beam in turn comprises a plurality of guides set along a longitudinal axis thereof orthogonal to the first axis and constituting a second axis of the machine. A carriage, carried by the mobile beam, is mobile on the guides of the mobile beam along the second axis. Finally, a column measuring head is carried by the carriage and is mobile with respect to this vertically along a third axis of the machine. The measuring head is designed to be equipped, at its bottom end, with a detector device of the contact or remote type.
In the measuring machines of the type described, the mobile beam is generally of considerable dimensions, with a length in the region of 3-4 meters and a cross section with dimensions in the region of 0.6 meters or more, in order to bestow the maximum possible rigidity thereon. To keep the mass of the beam within acceptable limits, said beam is made of a light alloy, for example an aluminium alloy. However, the dimensions of the cross section are such as not to enable use of conventional extrusion techniques. The beam must thus be obtained by casting, which entails high production costs for a twofold reason. In the first place, the process of casting in itself is more costly than extrusion; in the second place, the metallurgical properties of a rough beam obtained by means of casting are such as not to enable construction of the slide guides for the carriage directly on the rough beam via operations of machining (micromilling) and surface hardening. It is, instead, necessary to make a local deposition of material with appropriate characteristics, and subsequently carry out the mechanical finishing, and the guides can be made on the beam itself without entailing costly operations of deposition of material.